Recently, car stereos, CD players and other car audio devices are often stolen as much as their quality and grade have been elevated. In order to protect an audio device against pilferage, it is desired to provide a mechanism which releasably mount the audio device in an inner case fixed to a dashboard of a car to facilitate a user to readily remove the audio device from the inner case and bring it with him when he leaves the car. However, a significant strength of the dashboard itself is required against frequent removal of the audio device to protect inner mechanisms of the audio device.